C 肤对糖尿病大鼠坐骨神经结构和功能的影响

目的：探讨外源性C肽对Ⅰ型糖尿病大鼠坐骨神经结构及功能的影响。方法：选取Wistar大鼠40只,分为正常对照组（NC组）和糖尿病组（Dia组）,糖尿病组链脲佐菌素诱发大鼠成模后,再随机分为三组：糖尿病组（Dia组）、胰岛素治疗组（In组）和C肽治疗组（CP组）8周后,测定各组大鼠运动、感觉神经传导速度,并对病变大鼠的坐骨神经进行病理定量图像分析及超微结构分析,结果：1．In组、CP肽组与DM组相比：大鼠运动、感觉神经传导速度均明显增加（P〈0．01）;2．腓肠神经纤维的数量和总横截面面积也显著增加（P〈0.01）。3．CP组与In组相比运动、感觉神经传导速度也显著增加（P〈0．01）。4．电镜显示：Dia组有髓神经纤维髓鞘发生分离并有无颗粒囊胞状结构聚集现象,In组有髓神经纤维髓鞘分离现象明显减轻但仍有无颗粒囊胞状结构聚集现象．而CP组有髓神经纤维结构完全接近正常组。结论：C肽在改善糖尿病大鼠的神经结构和功能方面明显优于胰岛素．     

Transplantation of bone marrow-derived mononuclear cells improves mechanical hyperalgesia, cold allodynia and nerve function in diabetic neuropathy

Relief from painful diabetic neuropathy is an important clinical issue. We have previously shown that the transplantation of cultured endothelial progenitor cells or mesenchymal stem cells ameliorated diabetic neuropathy in rats. In this study, we investigated whether transplantation of freshly isolated bone marrow-derived mononuclear cells (BM-MNCs) alleviates neuropathic pain in the early stage of streptozotocin-induced diabetic rats. Two weeks after STZ injection, BM-MNCs or vehicle saline were injected into the unilateral hind limb muscles. Mechanical hyperalgesia and cold allodynia in SD rats were measured as the number of foot withdrawals to von Frey hair stimulation and acetone application, respectively. Two weeks after the BM-MNC transplantation, sciatic motor nerve conduction velocity (MNCV), sensory nerve conduction velocity (SNCV), sciatic nerve blood flow (SNBF), mRNA expressions and histology were assessed. The BM-MNC transplantation significantly ameliorated mechanical hyperalgesia and cold allodynia in the BM-MNC-injected side. Furthermore, the slowed MNCV/SNCV and decreased SNBF in diabetic rats were improved in the BM-MNC-injected side. BM-MNC transplantation improved the decreased mRNA expression of NT-3 and number of microvessels in the hind limb muscles. There was no distinct effect of BM-MNC transplantation on the intraepidermal nerve fiber density. These results suggest that autologous transplantation of BM-MNCs could be a novel strategy for the treatment of painful diabetic neuropathy.     

Motor and sensory nerve conduction velocities in Yucatan minipigs

Motor and/or sensory conduction velocities are used to assess peripheral nervous system disorders. Although the miniature pig represents a model of choice for long-term pharmacological experimentation, no study has so far been reported on this model in relation to the measurement of nerve conduction velocities. We developed the present technique and applied it to 34 3-18-month-old Yucatan minipigs. Motor and sensory conduction velocities were measured using the anterior tibial nerve and the internal plantar nerve, a branch of the posterior tibial nerve, respectively. The nerve conduction velocity data of motor (MNCV) and sensory (SNCV) nerves, together with the amplitude of the sensory nerve signal, were logarithmically dependent on the age of the tested animals (r(2)=0.92, 0.81 and 0.76, respectively). The mean values of MNCV and SNCV were 70.9 +/- 1.1 and 67.9 +/- 0.2 m/s, respectively, at the age of 16 months for these miniature pigs. In order to validate this model, we compared it with other known models when the velocities reached a plateau at the end of the study. These values were found to be higher than those in humans or rats, but are comparable to those of the baboon, one of the best large animal models for human pathologies. Because the physiology and metabolism of the minipig resemble those of humans, and due to its long lifetime, this animal represents a good model for studying the development of neuropathology.     

Treatment of diabetic polyneuropathy with the antioxidant thioctic acid (alpha-lipoic acid): a two year multicenter randomized double-blind placebo-controlled trial (ALADIN II). Alpha Lipoic Acid in Diabetic Neuropathy.

Short-term trials with the antioxidant thioctic acid (TA) appear to improve neuropathic symptoms in diabetic patients, but the long-term response remains to be established. Therefore, Type 1 and Type 2 diabetic patients with symptomatic polyneuropathy were randomly assigned to three treatment regimens: (1) 2 x 600(mg of TA (TA 1200), (2) 600)mg of TA plus placebo (PLA) (TA 600) or (3) placebo and placebo (PLA). A trometamol salt solution of TA of 1200 or 600 mg or PLA was intravenously administered once daily for five consecutive days before enrolling the patients in the oral treatment phase. The study was prospective, PLA-controlled, randomized, double-blind and conducted for two years. Severity of diabetic neuropathy was assessed by the Neuropathy Disability Score (NDS) and electrophysiological attributes of the sural (sensory nerve conduction velocity (SNCV), sensory nerve action potential (SNAP)) and the tibial (motor nerve conduction velocity (MNCV), motor nerve distal latency (MNDL)) nerve. Statistical analysis was performed after independent reviewers excluded all patients with highly variable data allowing a final analysis of 65 patients (TA 1200: n = 18, TA 600: n = 27; PLA: n = 20). At baseline no significant differences were noted between the groups regarding the demographic variables and peripheral nerve function parameters for these 65 patients. Statistically significant changes after 24 months between TA and PLA were observed (mean +/- SD) for sural SNCV: +3.8 +/- 4.2 m/s in TA 1200, +3.0+/-3.0m/s in TA 600, -0.1+/-4.8m/s in PLA (p < 0.05 for TA 1200 and TA 600 vs. PLA); sural SNAP: +0.6+/-2.5 microV in TA 1200, +0.3+/-1.4 microV in TA 600, -0.7 +/- 1.5 microV in PLA (p = 0.076 for TA 1200 vs. PLA and p < 0.05 for TA 600 vs. PLA), and in tibial MNCV: +/- 1.2 +/- 3.8 m/s in TA 1200, -0.3 +/- 5.2 m/s in TA 600, 1.5 +/- 2.9 m/s in PLA (p < 0.05 for TA 1200 vs. PLA). No significant differences between the groups after 24 months were noted regarding the tibial MNDL and the NDS. We conclude that in a subgroup of patients after exclusion of patients with excessive test variability throughout the trial, TA appeared to have a beneficial effect on several attributes of nerve conduction.     

补阳还五汤口服和药浴对损伤的大鼠坐骨神经传导速度的影响

目的探讨补阳还五汤口服加药浴对坐骨神经传导速度的影响。方法60只SD大鼠暴露左侧坐骨神经。对照组只钳夹;实验组钳夹并加用补阳还五汤口服及药浴治疗。观察钳夹前和钳夹切除后大鼠坐骨神经传导速度（SNCV）。结果于2、4、6周分别测对照组、实验组的坐骨神经传导速度（SNCV）。各时间段实验组坐骨神经传导速度恢复快于对照组,P〈0．01。结论补阳还五汤口服加药浴对坐骨神经传导速度有明显的促进作用。     

Nerve conduction velocity and spinal reflexes may change in rats after fumonisin B1 exposure

Mycotoxin fumonisin B1 (FB1) a natural inhibitor of ceramide synthase contaminating mainly the corn-based food and feed may cause dysfunctions in the nervous system. In the present study peripheral neural dysfunctions were biomonitored after dietary FB1 exposure in rats. Daily oral doses of 6.2 mg/kg body weight/day FB1 were applied in rats for 2 weeks. Before and after FB1 treatment nerve conduction velocities of tibial and sciatic nerves and spinal reflexes were analyzed in vivo. Electrophysiological recordings of biphasic plantar EMG (M and H components) and evaluation of sensory and motor nerve conduction velocities were carried out. Nerve conduction velocities revealed decreasing tendencies after FB1 exposure. The flexor reflex and the H-components of the extensor reflex were significantly reduced. The proposed in vivo biomonitoring can reveal functional impairment of the peripheral nervous system caused by mycotoxin exposure. Reduction of conduction velocity and altered reflexes after FB1 exposure are suspected to be associated with modified signal transmission due to toxic systemic effects and possible changes in sphingolipid metabolism.     

Treatment of diabetic polyneuropathy with the antioxidant thioctic acid (α-lipoic acid): A two year multicenter randomized double-blind placebo-controlled trial (ALADIN II)

Short-term trials with the antioxidant thioctic acid (TA) appear to improve neuropathic symptoms in diabetic patients, but the long-term response remains to be established. Therefore, Type 1 and Type 2 diabetic patients with symptomatic polyneuropathy were randomly assigned to three treatment regimens: (1) 2 × 600 mg of TA (TA 1200), (2) 600 mg of TA plus placebo (PLA) (TA 600) or (3) placebo and placebo (PLA). A trometamol salt solution of TA of 1200 or 600 mg or PLA was intravenously administered once daily for five consecutive days before enrolling the patients in the oral treatment phase. The study was prospective, PLA-controlled, randomized, double-blind and conducted for two years. Severity of diabetic neuropathy was assessed by the Neuropathy Disability Score (NDS) and electrophysiological attributes of the sural (sensory nerve conduction velocity (SNCV), sensory nerve action potential (SNAP)) and the tibial (motor nerve conduction velocity (MNCV), motor nerve distal latency (MNDL)) nerve. Statistical analysis was performed after independent reviewers excluded all patients with highly variable data allowing a final analysis of 65 patients (TA 1200: n = 18, TA 600: n = 27; PLA: n = 20). At baseline no significant differences were noted between the groups regarding the demographic variables and peripheral nerve function parameters for these 65 patients. Statistically significant changes after 24 months between TA and PLA were observed (mean ± SD) for sural SNCV: +3.8 ± 4.2 m/s in TA 1200, +3.0 ± 3.0 m/s in TA 600, -0.1 ± 4.8 m/s in PLA (p < 0.05 for TA 1200 and TA 600 vs. PLA); sural SNAP: +0.6 ± 2.5 μV in TA 1200, +0.3 ± 1.4 μV in TA 600, -0.7 ± 1.5 μV in PLA (p = 0.076 for TA 1200 vs. PLA and p < 0.05 for TA 600 vs. PLA), and in tibial MNCV: +1.2 ± 3.8 m/s in TA 1200, -0.3 ± 5.2 m/s in TA 600, -1.5 ± 2.9 m/s in PLA (p < 0.05 for TA 1200 vs. PLA). No significant differences between the groups after 24 months were noted regarding the tibial MNDL and the NDS. We conclude that in a subgroup of patients after exclusion of patients with excessive test variability throughout the trial, TA appeared to have a beneficial effect on several attributes of nerve conduction.     

Leprosy affects the tibial nerves diffusely from the middle of the thigh to the sole of the foot, including skip lesions

This study investigated where leprosy affects the posterior tibial nerve and whether neurolysis is beneficial. Nine patients with bilateral posterior tibial leprous neuropathy with no sensorimotor recovery were studied. Preoperative sensory-muscle and nerve conduction velocity testing revealed the tarsal tunnel to be the site of a severe lesion in all cases. During surgery, the most proximal site of the nerve lesion was detected by electrically stimulating the spinal roots from the second lumbar nerve to the fourth sacral nerve, evoking efferent mixed nerve compound action potentials that were recorded from the exposed tibial nerve. In all patients, the nerve compound action potentials became normal only proximal to the sciatic nerve bifurcation. Epineuriotomy within these seemingly unaffected segments revealed fibrosis of the interfascicular epineurium. Interfascicular neurolysis was performed on all affected segments. A 2-year follow-up showed an increase in girth of the proximal calf musculature in six of eight patients (the ninth patient had no recordable nerve conduction velocity). It was concluded that (1) leprosy affects the tibial nerves in a scattered way from the sciatic nerve main trunk distally to the exit of the tarsal tunnel; and (2) interfascicular, microsurgical neurolysis is beneficial provided that it is performed on all affected nerve segments.     

Slowing of Motor Nerve Conduction Velocity in Streptozotocin-induced Diabetic Rats is Preceded by Impaired Vasodilation in Arterioles that Overlie the Sciatic Nerve

Diabetes mellitus produces marked abnormalities in motor nerve conduction, but the mechanism is not clear. In the present study we hypothesized that in the streptozotocin (STZ)-induced diabetic rat impaired vasodilator function in arterioles that provide circulation to the region of the sciatic nerve is associated with reduced endoneural blood flow (EBF) and that these defects precede slowing of motor nerve conduction velocity, and thereby may contribute to nerve dysfunction. As early as three days after the induction of diabetes endoneural blood flow was reduced in the STZ-induced diabetic rat. Furthermore, after 1 week of diabetes acetylcholine- induced vasodilation was found to be impaired. This was accompanied by an increase in the superoxide level in arterioles that provide circulation to the region of the sciatic nerve as well as changes in the level of other markers of oxidative stress including an increase in serum levels of thiobarbituric acid reactive substances and a decrease in lens glutathione level. In contrast to the vascular related changes that occur within 1 week of diabetes, motor nerve conduction velocity and sciatic nerve Na⁺/k⁺ ATPase activity were significantly reduced following 2 and 4 weeks of diabetes, respectively. These studies demonstrate that changes in vascular function in the STZ-induced diabetic rat precede the slowing of motor nerve conduction velocity (MNCV) and are accompanied by an increase in superoxide levels in arterioles that provide circulation to the region of the sciatic nerve.     

Effects of thermal acclimation on nervous conduction and muscle contraction in the frog Rana temporaria

The effects of season and acclimation temperature on the latency of the leg withdrawal reflex and three of its components have been studied: conduction velocity in the sciatic nerve, spinal conduction time, and contraction time of gastrocnemius muscle. The latency of the leg withdrawal reflex was markedly shortened by cold acclimation: the reaction times were at 6 degrees C 1.54 s in 4 degrees C acclimated and 3.97 s in 24 degrees C acclimated winter frogs. Also, the temperature dependence of the reflex latency was reduced by cold acclimation. Thus, frogs acclimated to cold responded to external stimuli in cold more rapidly than warm-acclimated ones. This cold adaptation of the reflex could not be explained by changes in its studied components. These made up only one-tenth of the reflex response time, and either did not show significant cold acclimation (muscle contraction and spinal conduction times in summer) or showed inverse acclimation, especially when measured at high temperatures (i.e. conduction velocities were reduced by acclimation to cold). Thus, the cold acclimation of the reflex response probably resides in the sensory component of the response. The inverse temperature adaptation response of conduction velocities may reflect a reduced ion permeability across cellular membranes in cold which decreases metabolic energy expenditure during inactive periods.     

Peripheral mononeuropathy induced by loose ligation of the sciatic nerve in the rat: behavioral, electrophysiological and histopathologic studies.

The relationship between clinical parameters and pathological changes was investigated in an animal model of mononeuropathy, by behavioral, electrophysiological and histopathological methods. Mononeuropathy was induced in rats by loosely tying ligatures around the sciatic nerve. Eighty-four rats were used, and these were divided into fourteen groups to determine chronological changes in the withdrawal reflex latency, nerve conduction velocity and ultrastructure of the nerve from 1 to 84 days after nerve ligation surgery. Pathological changes around the ligated nerves were divisible in three phases: the first week was an inflammatory phase, when axonal degeneration, phagocyte infiltration and interstitial edematous changes were observed. The second and third weeks were a nerve-sprouting phase, when numerous axonal sprouts and remyelination were seen. The fourth to twelfth weeks were a recovery phase in which maturing myelination and interstitial fibrosis were characteristic. In the inflammatory phase, withdrawal reflex latencies were shortened, and sensory nerve conduction velocities (SCV) and motor nerve conduction velocities (MCV) gradually decreased. In the nerve-sprouting phase, the latency values remained low, and SCV and MCV were minimal. The parameters examined gradually returned to control levels during the recovery phase. In conclusion, these findings increase the knowledge of disease progression in mononeuropathy with hyperalgesia in human and animal models.     

The latency difference of the tibial and sural nerve sep: Peripheral versus central factors

The latency of the cortical SEP (CSEP) following stimulation of the posterior tibial nerve is nearly always shorter than the latency of the CSEP evoked by stimulation of the sural nerve. Till now this fact was believed to be due mainly to different conduction velocities within the peripheral nerves owing to the muscle afferents of the posterior tibial nerve. The surprising discovery that the lumbar and cervical SEPs exhibit much shorter time lags than the CSEPs led to the experiments described in this paper: during the registration of the peripheral sciatic nerve action potentials only slight differences in the conduction velocities were observed. Thereupon a topographical analysis was performed during which the minimum latency of the sural nerve CSEP was not measured at the usual C′_z electrode position but was found to be shifted to a more occipital and ipsilateral point.From these results it was concluded that, for the main part, the latency difference of the CSEPs results from ‘central factors’, which had already been postulated for the median nerve CSEP by Burke and coworkers.     

Hoffmann's reflex evoked on the soleus muscle and motor neural conduction velocity of the tibial nerve]

H reflex on the soleus muscle and motor tibial nerve conduction velocity are used to study peripheral nervous system maturation in 68 healthy children, from birth to 4 years of age. Proximal an distal conduction velocities develop in a parallel and approximately exponential way but proximal conduction velocities remain always faster. The latencies slightly decrease during the first 18 months of life and then increase very slowly.     

手足温针灸联合步行阶梯训练对老年糖尿病周围神经病变患者步态异常、血流动力学和感觉及运动神经传导的影响

摘要 目的：观察手足温针灸联合步行阶梯训练对老年糖尿病周围神经病变（DPN）患者步态异常、血流动力学和感觉及运动神经传导的影响。方法：按照随机数字表法将上海市第六人民医院2020年3月~2022年1月期间收治的119例老年DPN患者分为对照组（n=59,步行阶梯训练）和研究组（n=60,手足温针灸联合步行阶梯训练）。对比两组疗效、步态异常、血流动力学、临床症状改善情况和感觉及运动神经传导变化情况。结果：研究组91.67%的临床总有效率高于对照组72.88%（P<0.05）。研究组干预后的密歇根糖尿病神经病变评分（MDNS）和多伦多临床评分系统（TCSS）评分低于对照组（P<0.05）。研究组干预后的腓总神经及胫神经的感觉神经传导速度（SNCV）、运动神经传导速度（MNCV）高于对照组（P<0.05）。研究组干预后的全血黏度、血浆比黏度、纤维蛋白原低于对照组（P<0.05）。研究组足底压力中心轨迹（COP）曲线异常、全足平衡性曲线异常、全足压力变化曲线异常例数少于对照组（P<0.05）。结论：手足温针灸联合步行阶梯训练可促进老年DPN患者步态异常、血流动力学和感觉及运动神经传导恢复,疗效较好。     

Treatment with statins and involvement of the peripheral nervous system: results of a prospective clinical and neurophysiological follow-up

Aims: To study the pathological changes in neurophysiological examination of lower-limb peripheral nerves in patients with long-term statin treatment. Methods: Forty-two patients (23 males, 19 females, mean age 51.9 and 52.3 years) with a definitive diagnosis of combined hyperlipidemia were studied. Other metabolic disorders or chronic ethanol abuse were excluded. Initial examinations included laboratory and neurophysiological measures (peroneal and tibial nerves: MNCV, CMAP, Fwave mean latency; superficial peroneal and sural nerve: SNCV, SNAP). Subsequently, treatment with simvastatin 20mg daily was initiated. Patients were followed for 24 months with examinations at 1, 6, 12 and 24 months after statin treatment initiation. Results: None of the patients reported subjective symptoms typical for polyneuropathy. In laboratory findings, there was no elevation of muscle enzymes. Nevertheless, electrophysiological examination of lower-limb peripheral nerves demonstrated statistically significant prolongation of F-wave mean latency on peroneal and tibial nerves (p < 0.0001, paired t-test). A control group of 50 patients with combined hyperlipidemia but no statin treatment showed no changes over the same time interval. The study demonstrated that long-term Conclusions: The study demonstrated that long-term treatment with statins might cause a clinically silent but still electrophysiologically definite damage to peripheral nerves.     

灯盏生脉胶囊治疗糖尿病足临床观察

目的：探讨灯盏生脉胶囊治疗糖尿病足患者的临床效果。方法：选取76例糖尿病足患者,随机分为照组和试验组,各38例,对照组给予基础治疗与局部治疗,试验组在对照组基础上采用灯盏生脉胶囊口服治疗（每次0．36,3次／d）,共30天。比较两组患者的治疗效果、下肢血管彩超评分,以及治疗前后的溃疡面积、腓神经运动神经传导速度（MNCV）、感觉神经传导速度（SNCV）和2型糖尿病生活质量评分（DMQLS）的改变。结果：试验组治疗的总有效率明显高于对照组（P〈0．05）,下肢血管彩超评分疗效优于对照组（P〈0．05）;溃疡面积、MNCV、SNCV的改善优于对照组（P〈0．05）;DMQLS评分升高,与对照组比较,差异显著（P〈0．05）。结论：灯盏生脉胶囊治疗糖尿病足疗效确切,并能提高患者生活质量。     

Cobalamin and normal prions: A new horizon for cobalamin neurotrophism

It is known that cobalamin (Cbl) deficiency damages myelin by increasing tumor necrosis factor (TNF)-α and decreasing epidermal growth factor (EGF) levels in rat central nervous system (CNS), and affects the peripheral nervous system (PNS) morphologically and functionally. It is also known that some polyneuropathies not due to Cbl deficiency are connected with increased TNF-α levels, and that various cytokines (including TNF-α) and growth factors regulate the in vitro synthesis of normal prions (PrP^Cs). Given that there is extensive evidence that PrP^Cs play a key role in the maintenance of CNS and PNS myelin, we investigated whether the PrP^C octapeptide repeat (OR) region is involved in the pathogenesis of rat Cbl-deficient (Cbl-D) polyneuropathy. After intracerebroventricularly administering antibodies (Abs) against the OR region (OR-Abs) to Cbl-D rats to prevent myelin damage and maximum nerve conduction velocity (MNCV) abnormalities, and PrP^Cs to otherwise normal rats to reproduce PNS Cbl-D-like lesions, we measured PrP^C levels and MNCV of the sciatic and tibial nerves. PrP^C and TNF-α levels were increased in sciatic and tibial nerves of Cbl-D and saline-treated rats, and the OR-Abs normalized the myelin ultrastructure, TNF-α levels, and MNCV values of the sciatic and tibial nerves of Cbl-D rats. The same peripheral nerves of the otherwise normal PrP^C-treated rats showed typical Cbl-D myelin lesions, significantly increased TNF-α levels, and significantly decreased MNCV values. These findings demonstrate that Cbl deficiency induces excess PrP^Cs and thereby excess OR regions, which seem to be responsible for the PNS myelin damage, as has recently been found in the case of CNS myelin damage [66]. Furthermore, excess TNF-α is also involved in the pathogenesis of Cbl-D polyneuropathy. In conclusion, we have extended the list of prion diseases by adding one caused by excess PrP^Cs and the polyneuropathies related to excess TNF-α.     

Neuromuscular degenerative effects of Ankaferd Blood Stopper® in mouse sciatic nerve model

Purpose: Ankaferd Blood Stopper^® (ABS), a licenced medicinal herbal extract, is commonly used as an effective topical haemostatic agent. This study is designed to investigate whether topical ABS application may cause peripheral nerve degeneration and neuromuscular dysfunction in a mouse sciatic nerve model.

Methods: Twenty mice were randomly divided into two groups; an ABS treated experimental group and a saline-treated control group. Left sciatic nerves were treated with 0.3?ml of ABS in the experimental group and 0.3?ml of sterile saline in the control group for 5?min. Peripheral nerve degeneration and neuromuscular dysfunction were evaluated by behavioural tests, electrophysiological analysis and weight ratio comparison of target muscles.

Results: The motor function, assessed by the sciatic function index, was significantly impaired in ABS-treated animals as compared to the animals treated with saline. Motor coordination, evaluated with the rotarod test, was significantly decreased (–42%) in ABS-treated animals compared to the saline-treated animals. The degree of pain, assessed by the reaction latency to thermal stimuli (hot-plate test), was significantly prolonged (313%) in ABS-treated mice when compared to the saline-treated mice. ABS-treated mice showed a significant reduction in motor nerve conduction velocity (MNCV) (–52%) and the compound muscle action potential (CMAP) (–47%); however, it significantly prolonged onset latency (23%). The gastrocnemius muscles weight ratio of the ABS group was considerably lower than that of the control group.

Conclusions: These findings demonstrate that ABS triggers peripheral nerve degeneration and functional impairment and, thus promotes a deterioration of sciatic nerves.     

Ultrastructural relationship of quadriceps muscle degeneration with a distant peroneal nerve conduction in human myotonia dystrophica

The association of motor nerve conduction velocity (MNCV) to (1) duration of symptoms, (2) deep tendon reflex responses, (3) clinical muscle atrophy, and (4) ultrastructure of quadriceps muscle was studied in 18 patients with myotonia dystrophica of Steinert and nine normal controls. These patients had neither diabetes mellitus nor any other type of muscle dystrophy. Ultrastructural features of muscle fibers and intercellular spaces between atrophic fibers provided a basis for identifying degenerative changes and evaluating them semi-quantitatively. Our study indicates presence of an association between the pattern of muscle degeneration and both MNCV (correlation coefficients, gamma = +0.60) and duration of symptoms (gamma = -0.62), but not between MNCV and duration of symptoms (gamma = +0.28). Further analysis of the association between the degeneration of quadriceps and the MNCV of a distant peroneal nerve (which does not innervate quadriceps) suggested that the systemic nerve degeneration occurred in some groups of myotonia patients. Our study indicates that while in some patients the muscle degeneration may have been associated with the impairment of neurogenic elements, in others it occurred in the absence of any MNCV abnormality. Our findings favor the role of both neuropathic and myopathic factors in the muscle degeneration seen in myotonia dystrophica.